Addition of 1-Bromopropane to Clean Air Act Section 112 HAP List – What does it Mean?

The U.S. EPA published an advanced notice of proposed rulemaking (ANPR) on June 11, 2021 to address the impacts of adding 1-Bromopropane (n-propyl bromide or NPB) to the hazardous air pollutant (HAP) list in the clean air act (CAA).  The approval of the petition to add NPB as a HAP occurred about one year ago, while the regulatory process began in 2015 with a notice of a complete petition.  The ANPR is to solicit comments which can help U.S. EPA address the impacts of adding NPB as a HAP and comments are not requested about the decision to grant the petition to add NPB to the list of HAP.

What does this action mean to the regulated community?  It’s worth noting the significance of adding NPB as a HAP because once added, it will be the only substance added to the CAA HAP list (which currently has 187 substances) since the initial list was established under the 1990 CAA amendments.  The list has been relatively static (methyl ethyl ketone was removed in 2005), and the regulatory process to add compounds to the CAA HAP list is evolving as part of this action. Several considerations for implementation and how this action could impact your facility if you utilize NPB in a way that results in air emissions are presented below:

• NPB is a volatile organic compound (VOC). Once classified as a HAP, the potential HAP emissions from your facility will increase to include emissions of NPB.  Will your facility change status from an area source of HAP and become a major source of HAP?
• With a change from area source to major source of HAP, will additional air regulatory requirements apply, and what is the timing to come into compliance with those regulatory requirements?
• National emission standards for hazardous air pollutants (NESHAP) are promulgated at 40 CFR Part 63 to regulate HAPs or their surrogates. Existing standards may be revised to address NPB.  For example, 40 CFR Part 63 Subpart T – National Emission Standards for Halogenated Solvent Cleaning Solvents regulates solvents that are comprised of or contain specific compounds (e.g., methylene chloride, trichlorethylene, and others).  NPB could be added to the list of compounds regulated by Subpart T via a notice of rulemaking and associated comment process.
• Existing air permits may allow VOC emissions but preclude the use of HAP or certain quantities of HAP. Could a revision of your air permit be required to allow the use and emissions of HAP due to the classification of NPB as a HAP?
• Many states have rules or policies to regulate emissions of air toxic compounds that cover emissions of air contaminants that are neither regulated new source review (NSR) pollutants (such as nitrogen oxides or sulfur oxides) nor HAP. Could applicable state air toxics rules or policies require revision due to the classification of NPB as a HAP?  Will you now have to conduct air dispersion modeling of NPB air emissions?

U.S. EPA has indicated that they intend to add NPB to the list of CAA HAP by the end of 2021.  It will be interesting to see the timing and how implementation plays out.  Because HAP have never been added to the list, it will be interesting to see if the addition of NPB spurs any activity to evaluate and possibly add new compounds to the CAA HAP list (perhaps hydrogen sulfide), so even if you do not use or emit NPB, you may want to follow this action since it has implications for future additions to the HAP list.  If you have questions on the regulation of HAP emissions or how this future change could impact your environmental compliance, please reach out to me at nleone@all4inc.com or 610-933-5246 x121.